1) Field of the Invention
The present invention relates to a tremolo device for string musical instruments, in particular a guitar, which device is actuated to change the tension on all strings of the instrument to thereby produce a tremolo tone effect during a musical performance, and more particularly, it relates to a tremolo device that can be locked to prevent an undesirable changing of the string tension when the device is not used.
2) Description of the Related Art
As disclosed in U.S. Pat. Nos. 2,741,146 and U.S. Pat. No. 4,555,970, a tremolo device for a guitar, especially, an electric guitar, is well known and is used to continuously vary or cause a vibration of musical tones within a given range, as required by the player. As mentioned above, this tremolo tone effect is obtained by simultanously changing the tension on all strings of the guitar. Various types of tremolo device are known, for example, a synchronized type developed by the Fender Company; a "Bigsby" type developed by the Gibson Company; and a "Vibramute" type developed by the Mosrite Company, and these tremolo devices have basically similar constructions.
As shown in the afore-mentioned U.S. Patents, the tremolo device comprises a movable block member disposed in an opening formed in a soundboard or body of the guitar. The movable block member has a plate-like member fixed to a top thereof, and a bridge for anchoring the guitar strings is fixed to the plate-like member. The plate-like member is abutted against fulcrum elements fixed on a front surface of the guitar body, so that the movable block member is swingable about a swing axis perpendicular to the guitar strings. The movable block member is provided with counter balance tensile springs for providing a tension on the guitar strings, so that an equilibrium is established between the tension of the counter balance tensile springs and the tension on all of the guitar strings, whereby the movable block member is kept at a neutral position.
A tremolo handle is rotatably attached to the movable block member, and is rotatable between an operative position at which the tremolo handle can be manually operated by a player and an inoperative position at which the tremolo handle cannot be accidentally touched by the player. When the tremolo device is to be used, the tremolo handle is moved to the operative position, and by manually moving the tremolo handle toward and away from the front surface of the guitar body, the movable block member is swung about the swing axis perpendicular to the strings, whereby the tension on all of the strings is changed to thereby produce a tremolo tone effect during a musical performance. Namely, when the tremolo handle is moved toward the front surface of the guitar body, the strings are loosened, whereby the pitches thereof are lowered, and when the tremolo handle is moved away from the front surface of the guitar body, the strings are further tightened, whereby the pitches thereof are raised.
When the tremolo device is not to be used, the tremolo handle is moved to the inoperative position because, if the tremolo handle is left at the operative position, the player's hand may come into contact with the tremolo handle, and thus the pitches of the strings will be undesirably changed. As mentioned above, when the tremolo handle is at the inoperative position, it cannot be accidentally touched by the player.
Nevertheless, when the guitar is played in a special style, the pitches of the strings may be changed. In particular, for example, in a mute style, the player's hand rests on the bridge, and thus the movable block member may be pushed down and the pitches of the strings thereby raised.
U.S. Pat. No. 4,475,432 and Japanese Unexamined Patent Publication (KOKAI) No. 62-90695 disclose a tremolo device provided with a lock mechanism for locking the movable block member at the neutral position when the tremolo handle is moved from the operative position to the inoperative position. Specifically, the lock mechanism includes a collar member fixed to a root portion of the tremolo handle and having a latch element radially projected therefrom, and a catch member fixed to the front surface of the guitar body and having a slot for receiving the latch element of the collar member. When the tremolo handle is at the operative position, the latch element is disengaged from the slot of the catch member and the tremolo device can be actuated, and when the tremolo handle is rotated from the operative position to the inoperative position, the latch element of the collar member is engaged with the slot of the catch member and the movable block member is locked at the neutral position. Nevertheless, this lock mechanism fails to stably lock the movable block member at the neutral position, because the movable block member is merely locked at the side thereof to which the tremolo handle is attached. Namely, since the other side of the movable block member is not locked or constrained, the movable block member can be moved about the locked side thereof when the player's hand rests on the bridge, and thus the pitches of the strings may be raised while the player is performing, for example, in the mute style.